The middleware technology used as the foundation of Internet-enabled enterprise information systems is becoming increasingly complex. In addition, the various technologies offer a number of standard components architectures that can be used by designers as templates to build applications. However, there is little understanding in the software industry on the strengths and weaknesses of competing technologies, and the different trade-offs that various component architectures impose. This paper describes the approach being taken in CSIRO's Middleware Technology Evaluation (MTE) project to attempt to alleviate some of these problems. Specifically, this paper focuses on the scalability of transactional CORBA applications using the Visibroker Integrated Transaction Service v1.2. It discusses the methodology that has been developed, the application and environment used, and presents some performance results regarding the scalability of the Visibroker ITS.